U.S. patent application number 15/976080 was filed with the patent office on 2018-11-22 for tool holder.
The applicant listed for this patent is BOLLHOFF VERBINDUNGSTECHNIK GmbH. Invention is credited to Stefan Rehling.
Application Number | 20180333769 15/976080 |
Document ID | / |
Family ID | 62165356 |
Filed Date | 2018-11-22 |
United States Patent
Application |
20180333769 |
Kind Code |
A1 |
Rehling; Stefan |
November 22, 2018 |
TOOL HOLDER
Abstract
A C-shaped tool holder consisting of an integral frame structure
that is delimited by an inner and an outer edge, each C-shaped, in
which the C-shaped edges are made from and are connected to each
other by at least five multiple-vertex frame bodies that are
integrated into the frame structure, in particular triangles,
quadrilaterals and pentagons, wherein in each case an inner side of
the individual multiple-vertex frame bodies is a connecting
surface, continuously curving along a circumferential direction,
along the sides of the respective multiple-vertex frame body, and
the inner and the outer C-shaped edge is each delimited to the
outside by a continuously curving lateral surface.
Inventors: |
Rehling; Stefan; (Buckeburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOLLHOFF VERBINDUNGSTECHNIK GmbH |
Bielefeld |
|
DE |
|
|
Family ID: |
62165356 |
Appl. No.: |
15/976080 |
Filed: |
May 10, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 26/38 20130101;
B23K 2103/16 20180801; B23K 11/318 20130101; B21J 15/32 20130101;
B23K 2101/24 20180801; B23K 2103/10 20180801; B23K 26/40 20130101;
B23K 26/402 20130101; B21J 15/30 20130101; B21J 15/10 20130101;
B23K 2101/20 20180801; B23K 2103/04 20180801 |
International
Class: |
B21J 15/32 20060101
B21J015/32 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2017 |
DE |
DE102017110603.0 |
Claims
1. A C-shaped tool holder consisting of an integral frame structure
that is delimited by an inner and an outer edge, each C-shaped, in
which the C-shaped edges are made from and connected to each other
by at least five multiple-vertex frame bodies that are integrated
into the frame structure, wherein in each case an inner side of the
individual multiple-vertex frame bodies is a connecting surface,
continuously curving along the circumferential direction, along the
sides of the respective multiple-vertex frame body, and the inner
and the outer C-shaped edge is each delimited to the outside by a
continuously curving lateral surface.
2. The tool holder according to claim 1, the C-shape of which
consists of a first and a second leg arranged opposite each other
and a connecting leg, wherein the connecting leg connects the first
and the second leg to each other to form a C-shape.
3. The tool holder according to claim 2, the connecting leg of
which consists of at least two frame triangles and one
multiple-vertex frame body, and the first and second leg of which
each consist of at least one multiple-vertex frame body.
4. The tool holder according to claim 2, the connecting leg of
which consists of at least four frame triangles and one frame
quadrilateral, and the first and second leg of which each consist
of at least one frame quadrilateral or one frame pentagon.
5. The tool holder according to claim 3, the connecting leg of
which consists of at least four frame triangles and one frame
quadrilateral, and the first and second leg of which each consist
of at least one frame quadrilateral or one frame pentagon.
6. The tool holder according to claim 3, the multiple-vertex frame
bodies of which each enclose a surface that is surrounded by a bar
structure with a depth and a width, the depth of which is defined
orthogonally to the surface and the width of which is defined
parallel to the surface, wherein the depth surfaces of the
multiple-vertex frame bodies that are arranged opposite each other,
are spaced apart from each other by the width of the bar structure
and run parallel to the depth form continuously curving frame
surfaces.
7. The tool holder according to claim 6, the depth surfaces of
which, considered in the depth direction, form an inner and an
outer contour line per multiple-vertex frame body that are each
defined as a periodic fourth order NURBS curve on the basis of a
plurality of generated junction points at least in corner areas of
the respective multiple-vertex frame body.
8. The tool holder according to claim 3, the connecting leg of
which consists of at least four frame triangles and one frame
quadrilateral, and the first and second leg of which each consist
of at least one frame quadrilateral or one frame pentagon and the
multiple-vertex frame bodies of which each enclose a surface that
is surrounded by a bar structure with a depth and a width, the
depth of which is defined orthogonally to the surface and the width
of which is defined parallel to the surface, wherein the depth
surfaces of the multiple-vertex frame bodies that are arranged
opposite each other, are spaced apart from each other by the width
of the bar structure and run parallel to the depth form
continuously curving frame surfaces.
9. The tool holder according to claim 8, the depth surfaces of
which, considered in the depth direction, form an inner and an
outer contour line per multiple-vertex frame body that are each
defined as a periodic fourth order NURBS curve on the basis of a
plurality of generated junction points at least in corner areas of
the respective multiple-vertex frame body.
10. The tool holder according to claim 2 in which the first and the
second leg each has a free end, wherein a drive unit or an
attachment unit is provided integrally or modularly on at least one
end.
11. The tool holder according to claim 1 that is produced
integrally from metal or from a hybrid fiber-reinforced plastic
(FRP) or a fiber-plastic composite (FPC).
12. The tool holder according to claim 1, in which the
multiple-vertex frame bodies are triangles, quadrilaterals and
pentagons.
13. A joining device that has a C-shaped tool holder according to
claim 1 with a drive unit and a counter bearing.
14. The joining device according to claim 13, in which the joining
device is a rivet setting device and the counter bearing is a
die.
15. A design method of a C-shaped tool holder according to claim 1
with an integral frame structure that is delimited by an inner and
an outer edge, each C-shaped, with the following steps: a. Defining
a first and a second leg that are arranged opposite each other and
are connected with a connecting leg to form a C-shaped structure,
b. Forming the first and the second leg as well as the connecting
leg from at least five multiple-vertex frame bodies that are
connected to each other, and c. Forming a C-shaped outer edge and a
C-shaped inner edge of the tool holder consisting of the
multiple-vertex frame bodies that are connected to each other by a
continuously curving C-shaped outer lateral surface and a
continuously curving C-shaped inner lateral surface, as well as d.
Forming the individual multiple-vertex frame bodies each with a
continuously curving inner frame surface.
16. The design method according to claim 15 with the further steps:
Defining each multiple-vertex frame body in a common design plane
as a frame polygon and Defining an offset contour within the design
plane that is spaced apart on both sides from the frame polygon so
that the offset contour determines a width of the multiple-vertex
frame body within the design plane and is composed of two offset
polygons.
17. The design method according to claim 16 in which the width of
the offset contour on the individual sides of the frame polygon is
the same or different.
18. The design method according to claim 16 with the further steps:
Generating junction points at the corners and in the middle of the
sides of the offset polygons and Generating periodic fourth order
NURBS curves consisting of third degree polynomials on the basis of
the generated junction points.
19. The design method according to claim 15 with the further step
of computer-based implementing of the design method and creating a
computer-based data set for producing the tool holder.
20. A production method of a C-shaped tool holder according to
claim 1 with an integral frame structure, having the following
steps: a. Receiving a computer-based data set from a CAD system for
the C-shaped tool holder to be produced, b. Forwarding the
computer-based data set to a production machine, and c. Producing
and finishing the C-shaped tool holder according to the
computer-based data set.
Description
1. CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to German Patent
Application No.: DE 102017110603.0 filed May 16, 2017. The content
of this priority application is incorporated herein by reference in
its entirety.
2. TECHNICAL FIELD
[0002] The present disclosure relates to a C-shaped tool holder
consisting of an integral frame structure, in particular a C-frame,
as well as a joining device, in particular a rivet setting device,
which is made using the abovementioned C-frame.
3. BACKGROUND
[0003] In known joining or forming applications, the resulting
forces in the pressing, riveting or punching process must be
absorbed by an appropriate frame design. Frequently, C-frame
designs known for this purpose are used. In particular in the case
of automated processes in which such C-frame tools are driven by
robots, the weight of the C-frame plays a large role.
[0004] A C-frame known from the prior art is described in DE 699 11
040 T2. Such lightweight design C-frames are designs composed of
bar elements firmly connected in junction points (trussed frame).
These bar elements are designed in a triangle structure. To
optimize the material stresses under load in the junction points,
the bar elements are rounded by circular arcs in the junction
points.
[0005] Trussed frames possess good weight characteristics in
comparison to conventional compact structures or C-frames composed
of solid material. However, their stiffness against bending-up is
lower. This leads to a larger bending-up path as well as a larger
bending-up angle for a trussed frame with the same load and the
same outreach of the legs as for a conventional C-frame.
[0006] A too-large bending-up angle, however, is undesired in many
joining methods since it subjects the employed drive system to a
high lateral force strain. To reduce the bending-up angle in
trussed frames, the structure can be caused to deform in such a way
that the opposite, outer leg surfaces remain nearly parallel to
each other in the deformed state by suitably introducing the
process force outside of the truss junction points, as described in
the above document of the prior art.
[0007] Due to the still high weight load of, for example, the
robots in the case of known setting devices and C-frames, the need
for weight-reduced and therefore more mobile C-shaped tool holders
is great. Moreover, the demand for stiffness and load-bearing
capacity of the C-frame increases as its size stays the same or
decreases. It is therefore the object of the present invention to
provide a C-shaped tool holder that is more capable compared to the
prior art.
4. SUMMARY
[0008] In at least some embodiments, the C-shaped tool holder
consists of an integral frame structure that is delimited by an
inner and an outer edge, each of which is C-shaped. The C-shaped
edges are made from and connected to each other by at least five
multiple-vertex frame bodies integrated into the frame structure,
in particular triangles, quadrilaterals and pentagons, wherein in
each case an inner side of the individual multiple-vertex frame
bodies is a connecting surface continuously curving along a
circumferential direction along the sides of the respective
multiple-vertex frame body, and the inner and the outer C-shaped
edge is each delimited to the outside by a continuously curving
lateral surface.
[0009] The C-shaped tool holder, which in general is also referred
to as a C-frame in conjunction with, for example, rivet setting
devices or similar joining tools, is formed by an integral trussed
frame, meaning one that is not composed of individual parts. This
trussed frame, which consists of a plurality of frameworks, may be
carved out from a block of base material, for example milled from a
metal block, such as steel or aluminum, or a hybrid
fiber-reinforced plastic (FRP) or a fiber-plastic composite (FPC)
or a metal-fiber composite plastic hybrid.
[0010] The truss structure arises from the arrangement of a
plurality of multiple-vertex frame bodies in the interior of the
C-shaped tool holder which is enclosed by the inner and the outer
C-shaped edge of the C-shaped tool holder. The inner and outer edge
are spanned and connected to each other by the integrated
multiple-vertex frame bodies that are combined with each other. The
inner and the outer C-shaped edge is distinguished that the lateral
surfaces that face outwards, i.e., the lateral surfaces that face
outwards from the enclosed interior of the C-shaped tool holder,
run continuously curving. Preferably, the continuously curving
progression does not extend to the free ends of the C-shaped tool
holder. This continuously curving progression also applies for the
circumferential inner surfaces of the multiple-vertex frame bodies
that respectively enclose the empty spaces in the multiple-vertex
frame bodies. Due to this realized continuously curving progression
of the surfaces of the C-shaped tool holder, mechanical stress
loads of the individual bar elements within the C-shaped tool
holder are optimally distributed in the vicinity of the junction
points or intersections by an area of the bifurcation, meaning of a
transition area to other bar elements. Moreover, this continuously
curving progression of the surfaces achieves a reduction of
mechanical stress peaks in these transition areas that otherwise
are only decreased with the assistance of roundings between bar
elements that border each other.
[0011] According to an embodiment, the C-shape of the tool holder
consists of a first and a second leg arranged opposite each other
and a connecting leg, wherein the connecting leg connects the first
and the second leg to each other to form a C-shape. According to
another embodiment, the connecting leg consists of at least two
frame triangles and one multiple-vertex frame body. The first and
the second leg, which are arranged opposite each other, each
consist of at least one multiple-vertex frame body.
[0012] Depending on the use case of the C-shaped tool holder, the
first and the second legs as well as the connecting leg that
connects them can be differently dimensioned. Furthermore, with the
assistance of the number of the integrated multiple-vertex frame
bodies used to make the individual legs it is taken into account
which loads the tool holder must withstand. Moreover, a flexibility
or respectively stiffness of the tool holder adapted to the use
case is realized by designing the legs out of the multiple-vertex
frame bodies.
[0013] As an advantageous and preferred base design, the connecting
leg may be made from a central multiple-vertex frame body, in
particular a frame quadrilateral, and two frame triangles that
border it and are opposite each other. This design of the
connecting leg ensures a sufficient opening space of the C-shaped
tool holder. Moreover, a corresponding connection space is provided
in order to provide the first and second leg starting from the
connecting leg. Depending on the required length of the first and
second leg, these consist at least of one multiple-vertex frame
body, in particular a frame pentagon or a frame quadrilateral. In
the same way, it may also be preferred to provide the first and the
second leg from a frame quadrilateral in conjunction with a frame
triangle or from a frame pentagon in conjunction with a frame
triangle.
[0014] According to another embodiment of the tool holder, the
connecting leg is composed of at least four frame triangles and one
frame quadrilateral, while the first and the second leg are each
made from at least one frame quadrilateral or one frame
pentagon.
[0015] According to another embodiment of the tool holder, the
multiple-vertex frame bodies each enclose a surface that is
surrounded by a bar structure with a depth and a width. The depth
of the bar structure is defined orthogonally to the surface and the
width is defined parallel to the surface. Moreover, the depth
surfaces of the multiple-vertex frame bodies that are arranged
opposite each other, are spaced apart from each other by the width
of the bar structure and run parallel to the depth are continuously
curving frame surfaces.
[0016] The multiple-vertex frame bodies may consist of a plurality
of bars that are defined by the depth and the width. The number of
the bars that are connected to each other decides whether it is a
frame triangle, a frame quadrilateral or a frame pentagon.
Accordingly, a multiple-vertex frame body consisting of, for
example, four bar elements has two equally large surfaces spaced
apart from each other by the depth. These two surfaces are
delimited to the outside and in the direction of the free inner
space, meaning to the inside, by continuously curving frame
surfaces. Especially the continuously curving progression of these
frame surfaces causes the mechanical stress reduction and stress
introduction into the frame structure discussed above in order to
avoid disadvantageous mechanical stress peaks, for example in
junction points of bar elements.
[0017] Further, the depth surfaces of the tool holder may form an
inner and an outer contour line per multiple-vertex frame body
considered in the depth direction. This inner and outer contour
line is each defined as a periodic 4th order NURBS curve on the
basis of a plurality of generated junction points at least in
corner areas of the respective multiple-vertex frame body.
[0018] For designing the C-shaped integral tool holder, NURBS
curves may be used. The abbreviation NURBS curves refers to the
known non-uniform rational B-splines curves. The curves or surfaces
defined on this mathematical basis are part of known CAD systems
for modeling any shapes. This mathematical approach makes it
possible to undertake shape optimizations taking into
consideration, for example, material-specific constraints or
constraints defined by mechanical loads so that in addition to a
weight reduction, a stability optimization of the tool holder in
view of the respective use case is also possible. This may be
achieved by the continuously curving progression of the used frame
surfaces as well as by the deliberate displacement of junction
points to offset polygons (see below).
[0019] According to another embodiment, the tool holder has in each
case a free end on the first and on the second leg, wherein a drive
unit or an attachment unit is integrally or modularly provided at
at least one end. With the assistance of the free ends provided by
the first and the second leg, the tool holder may be usable, for
example, for a rivet setting device or another joining tool. While
the drive unit is attached to the one free end, a die or a
corresponding counter bearing is arranged, for example, on the
opposite free end.
[0020] According to another embodiment, the tool holder described
above consists of an integral structure that is made from the
following materials: a metal, in particular steel or aluminum, or a
hybrid fiber-reinforced plastic (FRP) or a fiber-plastic composite
(FPC) or metal-fiber composite plastic hybrid.
[0021] A fiber-plastic composite (FPC) (also: fiber-reinforced
plastic or fiber composite plastic, FCP) is a material consisting
of reinforcing fibers and a plastic matrix. The matrix surrounds
the fibers, which are bound to the matrix by adhesive interaction.
By using fiber materials, fiber-plastic composites have a
directionally dependent elasticity behavior.
[0022] Moreover, the present disclosure comprises a joining device,
in particular a rivet setting device, that has a C-shaped tool
holder according to one of the embodiments described above in
conjunction with a drive unit and a counter bearing, in particular
a die.
[0023] Furthermore, a design method of a C-shaped tool holder with
an integral frame structure is disclosed. This integral frame
structure is delimited by the inner and the outer edge, each
C-shaped. The design method has the following steps: defining a
first and a second leg that are arranged opposite each other and
are connected to each other by a connecting leg in order to form a
C-shaped structure; forming the first and the second leg as well as
the connecting leg from at least five, preferably seven,
multiple-vertex frame bodies that are connected to each other; and
forming a C-shaped outer edge and a C-shaped inner edge of the tool
holder consisting of the multiple-vertex frame bodies that are
connected to each other by a continuously curving C-shaped outer
lateral surface and a continuously curving C-shaped inner lateral
surface as well as forming the individual multiple-vertex frame
bodies each with a continuously curving inner frame surface.
[0024] The above design method is based on the approach of
constructing a contiguous C-shaped tool holder that is not composed
of individual frame elements. The result of this design method,
which exists in the form of electronic data, can then be passed on
to a CNC machine in order to carve out this integral C-shaped tool
holder from a solid base body, which may be steel, for example by
milling and similar machining methods or also by cutting methods
such as laser welding.
[0025] To provide the basic structure of the C-shaped tool holder,
its structure consisting of two legs that are opposite each other
and that are connected to each other by a connecting leg is spanned
by at least five multiple-vertex frame bodies. A multiple-vertex
frame body refers to a bar design with at least three sides defined
by these bar elements that are connected to each other integrally
at three corner points. Correspondingly, quadrilaterals, pentagons,
hexagons are constructible in the same way in order to make the
first and second leg and the connecting leg from these
multiple-vertex frame bodies. Furthermore, this C-shaped tool
holder is distinguished in that the entirety of the used
multiple-vertex frame bodies are connected to each other integrally
so that in the context of the production of the C-shaped tool
holder they neither have to exist as modular individual parts nor
be connected to each other by appropriate connecting means or
connecting methods in order to form the tool holder.
[0026] In another embodiment, the design method comprises the
further steps: defining each multiple-vertex frame body in a common
design plane as a frame polygon and defining an offset contour
within the design plane that is spaced apart from the frame polygon
on both sides so that the offset contour determines a width of the
multiple-vertex frame body within the design plane and is composed
of two frame polygons.
[0027] The C-shaped tool holder may be drafted in a common design
plane. Within this design plane, the multiple-vertex frame bodies
to be provided with each other in the integral frame structure form
frame polygons that are each connected to each other. A frame
polygon is a body with multiple vertices with at least three
corners. Depending on the position of the frame polygon in the tool
holder, this frame polygon can have any number of corners. The
majority of the frame polygons that are connected to each other
within the design plane form the base shape of the later tool
holder in the form of a line design. The individual lines of the
frame polygons are continued by bar elements running parallel to
them. These bar elements with their dimension with regard to width
and depth may take into account the mechanical constraints of the
tool holder to be employed in practice. That means that the bar
elements are formed taking into account later mechanical loads and
material configurations of the tool holder.
[0028] This bar structure, which may be initially likewise reduced
to a representation in the design plane, is represented with the
assistance of the aforementioned offset contour. Since only a
one-sided top view of the chosen bar elements is possible in the
design plane, the width of the individual bar elements or
respectively of the multiple-vertex frame body arises within the
design plane from two frame polygons that surround the fundamental
multiple-vertex frame body within the tool holder to be designed.
Accordingly, the intermediate space between two frame polygons
arranged opposite each other and the multiple-vertex frame body
situated between them may span the offset contour or the design of
the multiple-vertex frame body composed of bar elements.
[0029] Furthermore, the width of the offset contour along the
individual sides of the frame polygon may be the same or different.
The individual bar elements of the frame polygons or respectively
of the multiple-vertex frame bodies are dimensioned corresponding
to the expected and/or calculated mechanical loads of the tool
holder in the later practical use. This opens up the possibility
that an individual multiple-vertex frame body does not need to be
made from equally thick bar elements. Rather, load and deformation
states of the tool holder are taken into account and
correspondingly adjusted through different thicknesses of the bar
elements. As a result, the offset contour of the individual
multiple-vertex frame bodies initially has a constant width. In
comparison to each other, the width of different sides of the
multiple-vertex frame body can be formed differently or the
same.
[0030] Further, the design method may have the additional following
steps: generating junction points at the corners and in the middle
of the sides of the offset polygons and generating periodic
4.sup.th order NURBS curves consisting of 3.sup.rd degree
polynomials on the basis of the generated junction points. Based on
known mathematical principles, junction points are defined at the
corners and in the middle of the sides of the individual linear
sides of the offset polygons. These junction points form reference
points for periodic 4.sup.th order NURBS curves. The acronym NURBS
means in this context non-uniform rational B-splines curves. The
mathematical components and use possibilities are usual design
elements of, for example, CAD systems or similar software-based
design programs. Correspondingly, such a software-based NURBS
module is applied to practically realize the integral C-shaped tool
holder. These NURBS curves through the junction points optimize the
specified offset contour such that the integral frame structure is
adapted to the mechanical constraints.
[0031] Moreover, the above design method may comprise the
computer-based implementation of the design method, such as with a
CAD program, and the creation of a computer-based data set for the
production of the tool holder. This data set is transferable in the
known manner to processing devices or respectively their control
units in order to be able to produce the tool holder integrally
from one block of material.
[0032] The production method of a C-shaped tool holder with an
integral frame structure has the following steps: receiving a
computer-based data set from a CAD system for the C-shaped tool
holder to be produced, which may be as the result of the design
method described above; forwarding the computer-aided data set to a
production machine, such as a CNC machine or similar; and producing
and finishing the C-shaped tool holder according to the
computer-based data set.
[0033] Once the integral tool holder exists, its ends are also
equipped with a drive unit, such as a hydraulic or an electromotive
driven punch, and an appropriate counter bearing, such as a die or
the like.
5. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0034] Some embodiments of the present invention are described more
closely with reference to the accompanying drawings. They show:
[0035] FIG. 1 shows a schematic side view of an embodiment of the
C-shaped tool holder,
[0036] FIG. 2 shows a sectional enlargement from the tool holder
according to FIG. 1 in which continuously curving surface
progressions are compared to circular arc/line progressions,
[0037] FIG. 3 shows the enlarged view from FIG. 2 in which only the
continuously curving surfaces are shown,
[0038] FIG. 4 shows a schematic representation of an embodiment of
a design of the tool holder according to FIG. 1 composed of a
plurality of multiple-vertex frame bodies integrated into the frame
structure, each as a frame polygon,
[0039] FIG. 5 shows an assembly of the multiple-vertex frame bodies
according to FIG. 4 composed of multiple triangles, quadrilaterals
and at least one pentagon for designing the first and second leg
that are connected to each other by a connecting leg,
[0040] FIG. 6a-d shows a design of a multiple-vertex frame body
from the tool holder according to FIG. 1 based on a frame polygon
and an offset contour surrounding this frame polygon with
continuously curving side surfaces,
[0041] FIG. 7 shows an embodiment of a frame triangle designed from
a frame polygon and a surrounding offset contour with continuously
curving side surfaces that are defined by periodic 4th order NURBS
curves on the basis of a plurality of generated junction points in
the corner areas and in the middle of the sides of the offset
polygons,
[0042] FIG. 8 shows an embodiment of a triangular frame
polygon,
[0043] FIG. 9 shows an embodiment of the illustration of a
deformation of the frame polygon from FIG. 8 with an offset
contour,
[0044] FIG. 10 shows an embodiment of a frame polygon in the form
of a quadrilateral,
[0045] FIG. 11 shows a schematic illustration of a deformation of
the frame polygon according to FIG. 10 with the surrounding offset
contour,
[0046] FIG. 12 shows another schematic illustration of a
deformation of a frame polygon in the form of a pentagon with
offset contour,
[0047] FIG. 13 shows a schematic illustration of a deformation of
the tool holder from FIG. 1, and
[0048] FIG. 14a, b shows a comparison of mechanical stresses at a
junction point (A) with continuously curving connecting surfaces
between adjacent bar elements and (B) with circular arc/line
transitions, meaning continuously tangential transitions, between
adjacent bar elements that meet at the junction point.
6. DETAILED DESCRIPTION
[0049] The present disclosure relates to a C-shaped tool holder 1
as shown in FIG. 1 in a schematic side view according to an
embodiment. C-shaped tool holders 1 are generally known in view of
their use, for example in rivet setting devices or clinching tools.
They consist of one first 3 and one second leg 5 (see the
dashed-dotted line in FIG. 1) which run horizontally in FIG. 1 and
are connected to each other by a connecting leg 7 (dashed line in
FIG. 1).
[0050] The first 3 and the second leg 5 as well as the connecting
leg 7 consist of an integral frame structure 10. Within this frame
structure 10, they are integral with each other and do not exist as
connected or connectable leg modules. In this context, integral
means that the frame structure 10 forms a contiguous whole that is
not able to be dismantled into its individual parts without
destroying it. Correspondingly, the legs 3, 5, 7 are not connected
to each other by force-fitting, frictional or surface-bonded
connecting elements.
[0051] The integral frame structure 10 of the tool holder 1 is
formed by a plurality of bar elements 14 that are connected to each
other via intersections 12. A plurality of bar elements 14 each
encloses a free space 16 and thereby forms frame triangles 20,
frame quadrilaterals 22, frame pentagons 24 as well as
multiple-vertex frame bodies with more than five corners (not
shown). These are summarized as multiple-vertex frame bodies and
have any number of, but at least 3, corners.
[0052] To optimally control the deformation behavior of the tool
holder 1, the integral frame structure 10 is composed of a
combination of adjacent multiple-vertex frame bodies 20, 22, 24.
This results in a framework. The multiple-vertex frame bodies may
have 3, 4 or 5 corner points. In the first 3 and second leg 5,
which are also referred to as arms, preferably frame quadrilaterals
or frame pentagons alone or in conjunction with other
multiple-vertex frame bodies are employed to control the bending-up
behavior of the tool holder 1. In the connecting leg 7, a central
frame quadrilateral 22 may be used. This is combined according to
different embodiments with frame triangles 20 arranged opposite
each other, such as two or four (see FIG. 1).
[0053] In this design of the tool holder 1, its practical use
results in considerable mechanical stress loads in the bordering
bar elements 14 of the frame structure 10. To counteract this, in
the prior art bar cross-sections of the bar elements 18 are
correspondingly enlarged. This occurs either by individually
widening a used bar or overall by increasing the thickness of a
plate from which a C-frame is manufactured.
[0054] FIG. 2 shows a sectional enlargement from the frame
structure 10. The bar elements 14 may be connected to each other at
the intersections 12 by continuously curving connecting surfaces 30
(see continuous line in FIG. 2). The connecting surfaces 30 may be
determined with the assistance of periodic, continuously curving
4.sup.th order NURBS curves with variable curvature. Based on this
shaping of the transition areas between bar elements 14 at
intersections 12, mechanical stresses that appear near the
intersections 12 are optimally distributed across the area of the
intersection 12. Moreover, in this manner disadvantageous
mechanical stress peaks in this area are reduced or avoided.
[0055] It is also conceivable to connect adjacent bar elements 14
to each other in intersections 12 via roundings of bordering bar
element edges (see dotted line in FIG. 2). A rounding is a curve
segment with constant curvature that transitions to the straight
bar element edges tangentially continuously. Thereby, areas of
non-optimal mechanical stress distribution occur in transition
areas between the curve segment and straight bar element edges. In
this context, FIG. 14 shows a comparison of mechanical stresses
that occur at an intersection 12 with tangentially continuous
transition areas between bar elements 14 (see FIG. 14b) and the
same intersection 12 with continuously curving transition areas
(see FIG. 14a). The mechanical stress values show that the
intersection 12 with tangentially continuous transition areas
between the bar elements 14 is subjected to stronger mechanical
loads than the intersection 12 with continuously curving transition
areas.
[0056] FIG. 3 once again shows the sectional enlargement from FIG.
2 but only with continuously curving connections between adjacent
bar elements 14 in the area of intersections 12 (represented here
with a dotted line).
[0057] To design the tool holder 1, the connecting leg 7 is made
from at least two frame triangles 20 and one multiple-vertex frame
body 22; 24 and its first 3 and its second leg 5 are each made from
at least one multiple-vertex frame body 22; 24. It may also be
preferable to make the connecting leg 7 from at least four frame
triangles 20 and one frame quadrilateral 22, and to make the first
3 and the second leg 5 each from at least one frame quadrilateral
22 or one frame pentagon 24.
[0058] For a simplified representation of the make-up of the tool
holder 1, this is considered in the drawing plane of the
accompanying drawings. Correspondingly, the surface of the free
space 16 that is enclosed in a multiple-vertex frame body 20, 22,
24 lies in the drawing plane. The bar elements 14 have a width BB
and a depth TB. The width BB lies in the drawing plane and the
depth TB extends vertically into or out of the drawing plane.
Correspondingly, the free space 16 in a multiple-vertex frame body
20, 22, 24 may be surrounded by a depth surface, curving along a
circumferential direction, that is arranged vertically to the
drawing plane.
[0059] Under the assumption that the tool holder 1 has a constant
depth vertical to the drawing plane, the legs 3, 5, 7 are made from
a plurality of multiple-vertex frame bodies 20, 22, 24. These
multiple-vertex frame bodies 20, 22, 24 form the outer C-shaped
edge R.sub.a and the inner C-shaped edge R.sub.i. The outer R.sub.a
and the inner edge R.sub.i are formed by bar elements 14 of the
multiple-vertex frame bodies 20, 22, 24 of the integral frame
structure 10. Moreover, they are supported and connected to each
other by the bar elements 14 within the integral frame structure
10. The inner R.sub.i and the outer edge R.sub.a may be delimited
to the outside by continuously curving lateral surfaces that are
arranged parallel to the depth direction.
[0060] It is also conceivable here to use tangentially continuous
lateral surfaces.
[0061] To make the tool holder 1, the multiple-vertex frame bodies
20, 22, 24 are initially defined by frame polygons 30, 32, 34. The
frame polygons 30, 32, 34 have, depending on the embodiment, three
corners and three sides (see reference sign 30), four corners and
four sides (see reference sign 32), five corners and five sides
(see reference sign 34) or more. The corner points of the frame
polygons are connected to each other at the intersections 12. The
make-up described above of the legs 3, 5, 7 from the frame polygons
30, 32, 34 is illustrated in FIG. 5.
[0062] To optimally control the deformation behavior, the basic
structure of the C-frame is composed of a combination of adjacent
polygons. This results in a framework. The polygons have either 3,
4 or 5 corner points. In the arms of the C-frame, quadrilaterals or
pentagons may be employed to control the bending-up behavior. In
the middle area of the C-frame, a central frame quadrilateral is
used.
[0063] With this design of the tool holder 1, the disclosure
orients itself towards the example of nature, where loaded areas in
junction points of trusses (e.g., forked branches) are configured
like a continuously curving curve with variable curvature.
Therefore, the transition areas between two adjacent bar elements
14 may be configured with periodic, continuously curving 4.sup.th
order NURBS curves with variable curvature that optimally
distribute the stress progression of the bar elements 14 near the
intersection 12 over the area of the bifurcation and avoid stress
peaks in the transition area.
[0064] To further design the tool holder 1, reference is made to
the quadrilateral frame polygon 32 according to FIG. 6a. This
serves as an example for the further configuration of the frame
polygons 30, 32, 34 in the integral frame structure 10.
[0065] The frame polygons 30, 32, 34 of a basic structure according
to FIG. 5 are set by offset calculations of the individual edges
corresponding to a target strength of the later bar elements 14.
This results in the offset polygons 40 that specify approximately
the material contour of the later bar elements 40 of the integral
frame structure (see FIG. 6b).
[0066] The junction points 42 on the middle of the edge and on the
corner points of the offset polygons 40 are generated on the offset
polygons 40. These serve as junction points 42 for the NURBS curves
50. On the basis of the junction points 42, periodic 4.sup.th order
NURBS curves are generated that are represented by the reference
sign 50 and meet the requirements for the curve continuity. Frame
structures 10 optimized in this manner have, in addition to a
reduction of the load from mechanical stress, additional weight
advantages compared to the prior art since the employed material is
distributed optimally. With reference to FIG. 6d, FIG. 7 shows an
enlarged representation of the calculation of the integral frame
structure 10.
[0067] The aforementioned NURBS curve C(u) is generally known and
defined by the degree k, for example 3.sup.rd degree, of its basis
polynomials (=order p of the NURBS curve-1), an amount P of
weighted (w.sub.i) control points P.sub.i and a joint vector U.
NURBS curves and surfaces are generalizations of B-splines as well
as Bezier curves and surfaces. The main difference from these two
spline types is the weighting of the control points with the
weights w.sub.i. With the w.sub.i NURBS curves become rational.
[0068] The NURBS curve is fully defined by the sum of the control
points P.sub.i weighted with rational B-spline base functions
R.sub.i,k, by the formula
C ( u ) = i = 0 n R i , k ( u ) P i ##EQU00001##
[0069] The rational B-spline base function is calculated from
B-spline base functions N.sub.i,k of the degree of the basis
polynomial k, such as 3, and the weights w.sub.i associated with
control points as
R i , k ( u ) P i = N i , k ( u ) w i j = 0 n N j , k ( u ) w j
##EQU00002##
[0070] The parameter u.di-elect cons.[a, b] activates the
individual segments of the spline curves in the area of the joint
vector
V K = { a ( 0 ) , , a ( p - 1 ) p , u p , , u n , b ( n + 1 ) , , b
( n + p ) p } ##EQU00003##
[0071] The elements of the joint vector V.sub.K are monotonically
increasing, wherein all a.sub.(i)=a.sub.(j) as well as all
b.sub.(i)=b.sub.(j).
[0072] Similar calculations can be performed for NURBS surfaces
according to the following formulas:
S ( u , v ) = i = 0 n j = o n R i , j ( u , v ) P i , j
##EQU00004## R i , j ( u , v ) = N i , p ( u ) N j , q ( v ) w i ,
j k = 0 n l = 0 m N k , p ( u ) N l , q ( v ) w k , l
##EQU00004.2##
[0073] The design method described above may be computer-based,
meaning performed with the assistance of an appropriate software
program. Such software programs are generally known as CAD programs
and are a usual tool in design technology. Such software programs
and the computer-based systems that implement them may realize all
the computer-based activities in a design process. These include
geometric modeling, the calculating described above, simulating the
integral tool holder 1. Moreover, a design data set may be created
and given over to the production or respectively manufacturing.
These are, for example, CNC machines that implement the
computer-based data set into a product. In a similar manner, the
result of the design method can also be implemented into a
manufacturing drawing. Accordingly, the present invention also
comprises the production of the tool holder 1 based on the
computer-based, implemented design method above.
[0074] FIG. 8 shows a frame polygon 30 with three corners. To
obtain a frame triangle 20, the frame polygon 30 was surrounded
with the offset contour 40 (see above). When this frame triangle 20
is loaded by a force F according to FIG. 9, an angular bending-up
is thereby generated in the loaded corner area. This is indicated
by the arrow in FIG. 9.
[0075] A similar consideration of a frame quadrilateral 22 (see
FIG. 10) or a frame pentagon leads to a parallel bending-up in the
event of a mechanical load of a corner area. This is illustrated in
FIGS. 11 and 12 by a mechanical load with the force F. This load F
acts on the lower left corner of the frame quadrilateral 22 in FIG.
11 and of the frame pentagon 24 in FIG. 12.
[0076] It follows from this consideration that, based on the
appropriate choice of a frame quadrilateral 22 or a frame pentagon
24 instead of a frame triangle 20, the deformation of the integral
frame structure 10 under load can be deliberately adjusted towards
a parallel bending-up. Therefore, it may be preferred to employ
frame quadrilaterals 22 in the arms of the C-shaped tool holder 1,
meaning in the first 3 and in the second leg 5.
[0077] This adjustment of the deliberate parallel bending-up of the
tool holder 1 under mechanical load is illustrated in FIG. 13. Here
the difference of the frame structure designed from frame polygons
30, 32, 34 in the non-loaded state from the parallel-deflected
integral frame structure 10 demonstrates the deliberately
influenced deformation of the tool holder 1 by the force F.
REFERENCE SIGN LIST
[0078] 1 Tool holder [0079] 3, 5 First and second leg [0080] 7
Connecting leg [0081] 10 Integral frame structure [0082] 12
Intersection [0083] 14 Bar element [0084] 16 Free space [0085] 20
Frame triangle [0086] 22 Frame quadrilateral [0087] 24 Frame
pentagon [0088] 30 Frame polygon with three corners [0089] 32 Frame
polygon with four corners [0090] 34 Frame polygon with five corners
[0091] 40 Offset polygon [0092] 42 Junction point [0093] 50 NURBS
curve [0094] 60 Loaded frame structure [0095] L Length [0096] B
Width [0097] T Depth of the bar element 12
* * * * *